LOWERING CORTISOL ENHANCES GROWTH-HORMONE RESPONSE TO GROWTH-HORMONE RELEASING HORMONE IN HEALTHY-SUBJECTS

Cortisol is known to influence growth hormone release probably by modu lating somatostatin tone. We examined the effect of metyrapone (the 11 beta-hydroxylase inhibitor) treatment on growth hormone response to g rowth hormone releasing hormone (1 mu g kg(-1) body wt). Six healthy m ale subjects were tested on two occasions 1 wk apart. On one occasion they received metyrapone followed by growth hormone releasing hormone and on the other placebo followed by growth hormone releasing hormone. In all subjects metyrapone produced a significant drop in cortisol le vels. Together with this drop there was a significant enhancement of g rowth hormone response to growth hormone releasing hormone. The GH res ponse was negatively correlated with the cortisol level. Growth hormon e release in response to growth hormone releasing hormone challenge is thus seen to be heavily influenced by cortisol levels.